No sabre rattling as Marines rotate through NT

The Commandant of US Marines says the build-up of American forces in Australia's north is not designed to threaten other countries in the Asia-Pacific region.

The first contingent of 200 US Marines is due to complete a rotation through the Northern Territory next month after being stationed there since April.

By 2017, the US hopes to have 2,500 Marines stationed in the Top End for six months of the year.

The defence agreement between Australia and the US was announced after a visit to Darwin by President Barack Obama last November.

General James Amos, who is visiting Darwin's Robertson Barracks where the Marines are based, says it is about regional stability and cooperation, not sabre rattling.

"There is a lot of opportunity to work together: humanitarian assistance, disaster relief, training together and to actually have an influence on sea lines of communications, commerce, free trade, and responsible behaviour in the Asia-Pacific area.

"I don't look at it as sabre rattling at all."

General Amos, who is one of the US Joint Chiefs of Staff and is in charge of 200,000 US Marines, says there is no need to drastically ramp up the size of the US troop deployment in northern Australia next year.

"We look forward to next (northern) spring, after the rainy season, to the opportunity to bring in another rifle company, similar size, similar make-up," he said.

"It will be from another battalion in Hawaii."

Meanwhile, the Australian Defence Force says residents living near Darwin Airport won't be affected by a planned increase in the number of US fighter jets operating in the Top End.

ADF Major General Michael Krause says Darwin residents are already being affected by noise from defence exercises such as Exercise Pitch Black, which is being staged now.

He says the US jets will mostly use Tindal RAAF base near Katherine.

"We are very very aware of the noise issues in Darwin and there is no intention as part of the Force Posture Review and the increased Marine presence to add to that noise," he said.

"So, any jets that come as part of that will go elsewhere and we are looking at Tindal for that opportunity."

Free trade is the oldest argument in federal politics and the issue that literally defined the federation era but opposition exists to the TPP, courtesy of the Investor-State Dispute Resolutions clause.